Various heating methods of the related art may be implemented based on frequency characteristics. For example, high-frequency heating methods (e.g., heating methods implementing a frequency of 2.4 GHz or higher) induce a high-frequency electric field to spin electric dipoles in an object to be heated. The high-frequency electric field generates intermolecular friction between molecules of the object thereby generating heat. Such high-frequency heating methods may be divided into dielectric heating and microwave heating. Dielectric heating may be used in heaters, drying wood, bonding, defrosting, killing germs, and medical fields.
Low-frequency heating methods employ indirect heating to induce a current through an object (e.g., a conductor) using electromagnetic induction by interlinking magnetic fields through the object. In order to increase heating efficiencies using a low-frequency heating method, the object may be positioned within in the interlinkage of more magnetic fields by reducing the distance between a heating coil and the object. Such low-frequency heating methods may be used for thermal processing, thermal treatment, surface treatment, welding, indirect heating, or other various purposes.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.